Cooling device and method therefore for co2 washing machines

ABSTRACT

The present invention relates to a dry cleaning apparatus comprising an arrangement for cooling fluid being used as solvent in the apparatus, and a method for cooling the fluid. The cooling unit ( 3 ) is arranged so that it can cool the fluid by using

FIELD OF THE INVENTION

The present invention relates to dry cleaning systems namely washing machines using dry solvents such as carbon dioxide. In particular the present invention relates to a cooling device and method for cooling solvents being used in such systems.

BACKGROUND OF THE INVENTION

Washing systems using dry solvents such as carbon dioxide have been known for several years. In recent years this technology has become more popular mainly due to the environmental advantages compared to other washing systems using different solvents. Known dry cleaning systems usually contain a cleaning chamber wherein e.g. fabrics are cleaned, a distiller for separating the carbon dioxide from contaminants so that the carbon dioxide can be reused, a storage tank for storing the carbon dioxide when not in use for cleaning, a cooling unit, and a compressor for moving solvents in the system and for building up a pressure in the system. One example of such a system is disclosed in EP 1842602, which discloses a multiple bath CO2 system wherein the system and method is designed for processing parts in more than one bath of dense phase carbon dioxide. The system disclosed in EP1842602 is designed to work within a temperature interval between 10-20° C. which corresponds to pressure up to 58 bar. Currently the trend in this technology goes towards increasing the pressure in these systems in order to achieve advantages in the cleaning properties of the solvent being used.

A drawback with the prior art systems is that they use cooling arrangements such as plate heat-exchanger for cooling the fluids in the system. This type of cooling device uses refrigerants, for example R404 refrigerant, which is not environmental friendly. The use of this type or similar refrigerant is surrounded by governmental rules which therefore make it cumbersome to use. Furthermore it also increases the production cost since more complex solutions needs to be used in order to comply with the rules. Due to the low working temperatures of prior art system a further drawback is that the refrigerant needs to be cooled in order to have a cooling effect on the fluids in these systems.

BRIEF DESCRIPTION OF THE INVENTION

Thus it is an object of the present invention to provide an improved dry cleaning apparatus.

It is another object of the present invention to provide an improved cooling arrangement.

It is yet another object of the present invention to provide a technical solution that is simple.

It is even a further object of the present invention to provide a more environmental friendly solution.

The above objects and others are achieved by providing an apparatus and method having the characteristics defined in the independent claims. Embodiment of the invention are defined by the dependent claims.

According to a first aspect of the invention the above object and others are achieved by providing an apparatus for cleaning articles comprising, a compressor unit for processing fluid, a regulator associated with the compressor unit, for increasing pressure of the fluid between the compressor unit and the regulator, characterised by a cooling unit arranged between the compressor unit and the regulator for cooling of the fluid.

By having such an arrangement an improved dry cleaning apparatus can be achieved since the cooling unit for cooling the fluid can comprise a simpler solution compared to prior art. This is due to the increased pressure where the cooling unit is arranged. Preferably the cooling unit comprises water as coolant. The temperature of the water may be around room temperature such as around 20° C. or above. The water supply for the water used in the cooling unit as coolant can be taken directly from a duct, thereby water can be supplied on a need to have basis into the cooling unit.

The apparatus according to the invention may use a compressor unit comprising one, two or more compressor stages. Preferably the pressure after the compressor unit is about 70 bar or more.

The regulator may be any kind of device suitable to increase the pressure in the apparatus according to the invention. For example it may comprise a back pressure valve or an expansion valve. It may also comprise a valve for a fixed pressure increase such as a fixed counter pressure valve. Other solutions known to the person skilled in the art may also be used in order to increase the pressure in the arrangement according to the invention.

According to a second aspect of the invention the above objects and others are achieved by a method for cooling fluid being used as a solvent in a dry cleaning system, the method comprising the steps of: compressing the fluid, regulating pressure of the fluid, characterised in that the method further comprising the step of cooling the compressed fluid. By compressing the fluid and then cooling the fluid between the compressor and regulator a number of advantages can be achieved. For example a simpler and cheaper cooling solution can be used.

The cooling step preferably comprises cooling the fluid with water as coolant. Thereby a more environmental friendly solution can be achieved. As mentioned above the water may be room tempered and directly supplied from a duct on a need to have basis.

The regulating step according to the invention preferably comprises the step of increasing the pressure. So that a higher pressure is build up in a certain part in the apparatus. In particular the pressure is increased where the cooling step takes place in the system, before the fluid is transferred to the storage device.

The method may further comprise a second cooling step comprising a pressure decrease. When the fluid passes the regulator into the storage device a decrease of the pressure of the fluid may take place. This further cools down the fluid that is to be stored in the storage device.

These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF FIGURES

FIG. 1 illustrates an embodiment of the apparatus according to the present invention comprising an arrangement of a regulator and cooling unit

FIG. 2 illustrates the apparatus according to the present invention during fluid evacuation, where the fluid is in gas phase.

FIG. 3 illustrates the apparatus according to the present invention during distillation.

FIG. 4 illustrates an embodiment of the present invention in an apparatus having a two stage compressor solution.

FIG. 5 illustrates method steps according to the present invention.

Figures are preferably schematically drafted in order to facilitate understanding. Therefore other designs that could be drafted in the same schematic way are implicitly also disclosed in this document.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 shows a dry cleaning apparatus according to the present invention comprising a storage device 1, a compressor 2, a cooling unit 3, a cleaning chamber 4 for cleaning fabrics, a distiller 5, a refill tube 6 and a regulator 7. The dry cleaning apparatus preferably uses carbon dioxide as solvent fluid which is stored in the storage device 1.

When a cleaning program is started the fluid is transferred via pipes to the cleaning chamber 4 in order to clean the articles that are present in the cleaning chamber 4. In order to have the fluid in the right phase where the cleaning effect is as effective as possible the compressor unit 2 builds up a pressure in the apparatus.

However the compressor unit 2 does not necessarily directly influence what phase the fluid is in, within the cleaning chamber 4, during e.g. a cleaning process. This is dependent on the temperature and/or pressure in accordance with the ideal gas law or related laws. For example the temperature can be decided by the pressure or the other way around. Thus in some parts of the system the fluid may be in a liquid state or in a gas state or in both liquid and gas state, depending on the pressure and temperature.

Before the fluid is transferred to the storage device 1 after cleaning, the fluid is first distilled in the distiller 5 in order to remove contaminants from the fluid. Thus in the distiller 5 the fluid is heated so that it gasifies and thereby can be removed from the distiller 5 without the contaminants. Before the fluid is transferred into the storage device 1 it has to be cooled in the cooling unit 3.

In order to be able to use room tempered water as coolant, the pressure on the fluid has to be at a certain level so that the water provides a cooling effect on the fluid. For this purpose the pressure of the fluid passing the cooling unit is increased by a regulator 7 so that the temperature and pressure of the fluid is 35° C. or more and 70 bar or higher. By increasing the pressure and hence also the temperature to these levels it is possible to use room tempered water as coolant. Thereby it is no longer necessary to use refrigerants such as R404 and other cooling means to achieve the same.

Room tempered water is about 20° C. or above, however it can also be cooler such as between 15° C.-20° C. As long as the water is cooler than the fluid it is supposed to cool, a cooling effect can be achieved. Thus this makes it possible to use water as coolant directly supplied from a duct. Thereby as long as the apparatus is connected to a water supply duct, coolant will always be present. Coolant can also be requested on a need to have basis automatically by the apparatus according to the invention.

Furthermore other fluids which are liquid at room temperature and which are environmental friendly may also be used for cooling.

As mentioned earlier the regulator 7 can either be of a variable active type that regulates the pressure independently of the pressure after the regulator 7. Thus, the pressure before the regulator 7 is set to a fixed level (e.g. 70 bar) independently of the pressure after the regulator 7. Hence the delta (Δ) value of the pressure before and after the regulator 7 is variable. The regulator 7 may also be of a fixed type that ensures a fixed pressure difference, delta (Δ) pressure, before and after the regulator 7, such as +5, +10 or +15 bar, based on the pressure after the regulator 7.

FIG. 2 illustrates an embodiment according to the invention during evacuation of fluid from the cleaning chamber 4. The compressor 2 evacuates the fluid, in gas phase, from the cleaning chamber 4 by building up the pressure after the compressor 2. This is achieved by the regulator 7, thereby the fluid can be cooled by water in the cooling unit 3. Preferably the regulator 7 regulates the pressure so that the pressure of the fluid is 70 bar or higher before the regulator and about 55-60 bar after the regulator 7.

FIG. 3 illustrates the apparatus according to the invention during distillation activity. During distillation, gas is transferred from the distiller 5 via the compressor 2. The compressor 2 increases the pressure of the fluid and thus also the temperature of the fluid. The fluid is transferred via pipes through the distiller 5 in order to use the heat in the pressurised fluid to evaporate the fluid in the distiller 5. Thereafter the fluid is transferred to the cooling unit 3 for cooling and then transferred to the storage device 1 via the regulator 7. Since the pressure decreases after the regulator 7, a further temperature decrease is achieved when the fluid enters the storage device 1.

FIG. 4 depict an apparatus according to the invention comprising a compressor unit 2 comprising two compressor stages.

FIG. 5 shows a method according to the invention comprising a pressure increase step 8, a regulation step 9 wherein the pressure is regulated by the regulator 7 so that an increase of the pressure is achieved, and a cooling step wherein the pressurized fluid is cooled by the cooling unit 3.

In the above description the term “comprising” does not exclude other elements or steps and “a” or “an” does not exclude a plurality.

Furthermore the terms “include” and “contain” does not exclude other elements or steps. 

1. An apparatus for cleaning articles comprising, a compressor unit (2) for processing fluid, a regulator (7) associated with the compressor unit (2), for increasing pressure of the fluid between the compressor unit (2) and the regulator (7), characterised by a cooling unit (3) arranged between the compressor unit (2) and the regulator (7) for cooling of the fluid.
 2. An apparatus according to claim 1, wherein the cooling unit (3) comprises water as coolant.
 3. An apparatus according to claim 2 wherein the temperature of the water is above 20° C.
 4. An apparatus according to claim 1, wherein the compressor unit (2) comprises two or more compressor stages.
 5. An apparatus according to claim 1, wherein the regulator (7) comprises a back pressure valve.
 6. An apparatus according to claim 1, wherein the regulator (7) comprises an expansion valve.
 7. An apparatus according to claim 1, wherein the regulator (7) comprises a fixed counter pressure valve.
 8. A method for cooling fluid being used as a solvent in a dry cleaning system, the method comprising the steps of: compressing the fluid, regulating pressure of the fluid, characterised in that the method further comprising the step of cooling the compressed fluid.
 9. A method according to claim 8, wherein the cooling comprises cooling the fluid with water as coolant.
 10. A method according to claim 8, wherein the regulating step comprising the step of increasing the pressure.
 11. A method according to claim 8, wherein the method further comprising a second cooling step comprising pressure decrease. 